No compression : the piston clould have a hole in it or the top off off it , a valve is burnT really bad letting the compression leak by it , or you might have droped a valve destroying the top of the piston , if it was bad rings I thing you would be getting a little bit of a reading on your compression guage , the rod cap could have came off and the piston is not even going up and down to create compression
Thank you for the Question I hope I Answered it For you
